Disturbing details of jail murder-suicide revealed

The ABC has uncovered disturbing details of a murder-suicide at Sydney's Silverwater Jail which have raised serious questions about the actions of prison staff and left a family desperate for answers.

The deaths of father-of-three and boat salesman Nick Michael Karayiannis, 41, and his cellmate Tien Tran, 47, have been shrouded in mystery since prison guards discovered their bodies during a morning headcount on Easter Monday.

But the ABC has learned Karayiannis was found with a bag over his head and his hands tied to the beds on either side of the cell.

An autopsy has found he was asphyxiated before his alleged murderer hanged himself.

Karayiannis's lawyer, Rod Van Outen, says a prisoner in a nearby cell claims he heard cries for help beforehand.

"What's concerning is if that was true, no-one went to Nick's rescue," he said.

"Guards should have been checking their cell regularly.

"You don't expect to go inside and come out in a box. He should never have died."

Karayiannis had been held at Silverwater Jail for less than a month, fighting charges of drug manufacture and preparing to apply for bail.

His family has told the ABC he had already intervened in two suicide attempts by his cellmate.

Karayiannis had raised concerns about Tran's mental health with his lawyer.

"I met with him a week before his death," Mr Van Outen said.

"He was in good spirits and he said, 'Everything is fine, except I'm sharing a cell with a nutter.'"

Family members have engaged lawyers to investigate the deaths.

But the barrister for Mr Karayiannis' sister and parents, Patrick Lott, says, "police have provided very little information to the family to date."

Tran had been in custody since late February on a charge of importing a commercial quantity of drugs.

The union representing prison officers says the 47-year-old should have been placed under isolation and constant monitoring, according to the corrective services department policy for inmates with serious mental illness.

"The staff who responded to the situation that morning are still traumatised by the matter," the Public Service Association's Matt Bindley said.

"It's something they'll live with forever."

Call for inquiry

A coronial inquest will be held but the New South Wales opposition's justice spokesman, Paul Lynch, is calling for a broader inquiry.

"What I want is a public inquiry carried out with full judicial powers to get to the bottom of what occurred," he said.

"It seems to me that there may well be a number of systemic issues involved in the incident.

"It seems that this was eminently preventable."

Mr Bindley, the chairman of the Public Service Association's prison officers branch, is backing the push for a judicial inquiry.

"My major concern with the whole department is that we have too many inmates with not enough beds," he said.

In a statement, a spokeswoman for Corrective Services NSW (CSNSW) says the department is closely cooperating with the police investigation into the murder-suicide.

"All claims surrounding this matter will be fully investigated and any necessary action implemented prior to a coronial inquiry," she said.

"CSNSW will also very carefully consider any recommendations by the coroner that may arise."

NSW Attorney-General Greg Smith and the NSW Police have declined to comment because a coronial inquest is pending.

Karayiannis' family is still in shock. In a statement, their barrister Patrick Lott says: "The family are mourning the loss of a son, a brother and a father."

"At this point in time, the family do not wish to speak with the media," he said.

"The family have instructed lawyers in order that questions are asked and answered about the circumstances surrounding the death of Nick Karayiannis."